The present invention relates to a video processing circuit for adjusting video luminance and chrominance levels as well as chroma hue, and particularly to such a circuit for selectively adjusting these factors relative to synchronizing information without reconstituting the latter.
It is frequently desirable to adjust the various components of a color video signal relative to one another, to suit individual preference or to compensate for misadjustment of other circuitry. Thus, one may wish to adjust the video output from video camera equipment, or adjust the input or output of a video recorder to improve transmission or recording capabilities as well as for improving picture quality. Although adjustments are usually available on television receiving or tuning equipment, alteration of the video signal may be desired between a tuner and hard-to-reach television projection equipment.
Heretofore, video processing circuitry of this type has often been expensive and designed primarily for the professional user. Usually the synchronization information, i.e. the horizontal and vertical synchronizing pulses, color burst, etc. are reformed or regenerated, while the video luminance and chrominance information is separately adjustable. Time delays are usually associated with the reconstituted sync and proper blanking in the video signal may be somewhat clumsy.
Unfortunately, the equipment heretofore provided for the professional market is not appropriate for adjusting signals of various levels from a wide variety of equipments as may be encountered by the consumer or home user of video apparatus. The professional equipment usually generates a synchronization pulse of predetermined amplitude and consequently the remainder of the video signal must be adjusted relative thereto.